In vivo biodistribution of AUNPs after PDT

To track the in vivo distribution of AUNPs, Maestro in vivo imaging system (CRi, Inc., Woburn, USA) using a 980 nm laser as the excitation source was utilized to obtain AUNPs signals from mice. 

1. B16F10 tumor cells were injected into the right flank of mice to build melanoma mouse model. 

2. After about 10 days, B16F10 tumor-bearing mice (n = 3) were intratumorally injected with 30 μL of AUNPs or pAUNPs (0.5 mg/mL, based on TPEBTPy), respectively. 

3. At 6 hours post-injection, the mice were anesthetized with 2% (v/v) isoflurane and the tumors were irradiated with 980 nm NIR laser (0.6 W/cm²) for 10 min (with 1 min interval for each minute to avoid heating effect). 

4. Subsequently, the mice were immediately imaged with a Maestro in vivo fluorescence imaging system at different time points (CRi, Inc., Woburn, USA).

5. The autofluorescence was removed by spectral unmixing software and fluorescence signals were quantified by the Maestro system (Emission filter: 850 nm short-pass; Acquisition setting: 600 to 900 in 10 nm steps; Exposure time: 10 s). 

6. In addition, the tumor-bearing mice were also sacrificed at 24 h post-irradiation, and the DLNs in different groups were collected, imaged and quantified by the Maestro system. (Excitation filter: 455 nm; Emission filter: 672 nm longpass; Acquisition setting: 500 to 900 in 10 nm steps; Exposure time: 300 ms).